Description:
A young American art student, Sarah, who unwittingly opens an ancient urn that unleashes the demonic power of the world's most powerful witch. As a scourge of suicides plague the city and witches from all over the world converge on Rome to pay homage, Sarah must use all her own psychic powers to stop the 'Mother of Tears' before her evil conquers the world.

Qvamp says:

The main character gets help from a White Witch, who happens to be a lesbian, though it's not a plot point. She goes to her house and makes love to her girlfriend at one point.

There are also inclinations that the Evil Witch of the story is pan-sexual.